Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Goes well beyond the annotations: nothing is charged until the person pays, a link is emailed to them, the spot is held for a week, and the call requires the billing:checkout scope. The 'holds a week's spot' line also hints at a persistent side effect, consistent with readOnlyHint=false and idempotentHint=false.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

Roughly four dense sentences, front-loaded with the action and its source. Every clause carries information, though the em-dash parentheticals make it slightly harder to scan than a plain enumeration.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Covers the mutation's side effects, authorization scope, human handoff, and validity window; an output schema exists so return values need no explanation. Nothing an agent needs in order to call this correctly and safely is missing.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 100%, so every parameter is already documented, including the week/weeks pairing and the 4-week maximum. The description only restates the provenance of 'item' (from get_pricing) and adds the listing-approval precondition; it says nothing extra about week, weeks or coupon semantics.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific verb and resource ('Start a checkout') plus the actor scope ('for the person you act for'), and ties the input to a named sibling ('an item from get_pricing'). An agent can distinguish this from get_pricing, get_launch_options or choose_launch without opening any schema.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

Explicitly says to source the item from get_pricing and that a placement requires the listing to be approved first, which are real preconditions. It also defines the agent's role ('you never pay'), routing the output to the human. It stops short of naming alternatives for the same goal, but the precondition chain covers the main decision.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.